Which of the following is not an effect of erosion on lakes?
a. water leakage
b. wearing away of sides
c. increased water levels
d. basin filling with sediment

I just took the test and the correct answer was C- Increased water levels

Magma is outside the volcano  and lava is inside the volcano. 

Geothermic gradient is the rate of increasing temperature with respect to increasing the depth in the earths interior. away from tech tonic plates boundaries, it is about 25-40 c/km (72-87 degrees f/mi) of depth near the surface in most of the world.